How to set rest pose as pose?
In Outliner change to "Current Scene" in dropdown, r/click on
"metarig" and click "Delete heirarchy". You have two identical rigs
and meshes, although metarig only shows origins suggesting you
deleted in edit mode. Irrespective, it messes with your active rig.
Select your mesh and apply rotation and scale (ctrl-a).
In pose mode select shin.l and delete the Limit Rotation constraint. In the IK panel set the Pole Angle to 0.
In pose mode select shin.r and set the pole angle to 0.
Ditto forearm.l, set pole angle to 90
Ditto forearm.r, set pole angle to -90


edit: formatting